plastic found in burger

i purchased a zinger burger reg meal Friday evening at about 23h30 while at home eating half way through my burger i found a hard sort of plastic i think its from a sauce bottle or something in the burger i mean really where are they preparing the food on the floor or maybe next to the dustbin? i what else gets tossed in our meals that we don't know about makes you wonder. Needless to say i wasted my money as i could not finish the burger and threw it away, really nauseating